1. Field of the Invention
The present invention relates to a liquid jet recording apparatus which is made compact by utilizing a rotary type conveying belt or roller as a conveying member of the recording medium, and especially relates to a full line recording apparatus whose recording head is enlarged, or full color recording apparatus whose recording area is increased.
2. Related Background Art
Liquid jet recording apparatuses (ink jet recording apparatuses) each of which can perform the recording of information such as characters and/or images by discharging recording liquid from a recording head have widely been known.
A recording medium mainly receiving the recording comprising a paper or a plastic sheet has been used with the liquid jet recording apparatus of this kind. Such liquid jet recording apparatus has been adopted to a recording output apparatus of a computer, word processor and the like, since it has less noise in the recording operation and simpler mechanical construction and is more inexpensive, than other recording systems.
However, in such liquid jet recording apparatus, since the recording is performed by directly discharging the recording liquid (referred to as "ink" hereinafter) from a nozzle of the recording head, special attention must be paid to always keep the ink in a dischargeable condition, which is not needed in other recording systems.
That is to say, since the ink exists in the nozzle of the recording head even when the apparatus is in an inoperative condition, it's necessary to prevent the ink in the nozzle from drying, and the change in quality of the ink, for example, due to increase in the viscosity of ink caused by evaporation of moisture in the ink must also be prevented. To this end, a socalled capping means for covering the orifice of the recording head by means of a cap thereby preventing the drying and/or evaporation of the ink in the inoperative condition of the recording apparatus has been proposed.
However, under the low moisture condition, or when the recording apparatus is not operated for a long time, the increase in the viscosity of ink cannot be avoided adequately only by the capping means. Accordingly, as well as the capping means, there has been provided a head restoring mechanism which produces the negative pressure in the orifice of the recording head by sucking the air within the cap covering the recording head so that the ink remaining in the nozzle of the recording head is drawn out or which produces the pressure in the nozzle by means of a pump and the like so that the deteriorated ink is discharged from the orifice of the recording head.
Further, in some cases, the quality of the ink in the unused nozzle or nozzles is changed or deteriorated even during the recording operation.
That is to say, in the ink jet recording apparatus having a plurality of recording heads, there will be a orifice or orifices which are not used for a long time even during the recording operation in accordance with the kind of the information to be recorded. More particularly, in some nozzle or nozzles, the time interval between the discharge of the ink and the next discharge of the ink will be very long. In this way, the discharge frequencies or periods of the ink from the respective nozzles vary in relation to each other. Therefore, in the nozzle having the lesser discharge frequency or longer time interval between two successive ink discharges, the viscosity of the ink will be increased due to the drying thereof according to the surrounding conditions such as humidity and/or temperature, which results in the unstable discharge or the non-discharge of the ink from the nozzle.
To avoid this, the idle discharge, or pre-discharge has been carried out (for non-recording purpose) from each nozzle toward an ink absorbing member provided in the capping means for predetermined time intervals.
In addition, in a recording apparatus adopting one of full line or color recording, or in full line scan type requiring high speed recording "fog" like mist is generated in the recording area space formed between the recording head and the recording medium upon recording because a large amount of ink advances toward the recording medium. The technique adopting attracting means for solving the above problem has been known.